How do Adaptive Headlights Work? Are Adaptive Headlights Worth It?

How headlights illuminate the road ahead isn’t always so simple. Besides using brighter and more efficient bulbs, many new headlights actively adapt to changing road conditions. Adaptive headlights let drivers see farther, around corners, and past traffic. But how exactly do they work?

Adaptive headlights are headlights that actively respond to changing conditions. Their goal is to provide drivers with better visibility and more time to react to conditions ahead. It’s a term that encompasses several different features, most common of which is curve-adaptive headlights. These headlights have bulbs that pivot in accordance with the vehicle’s direction of travel—and sometimes speed.

The term adaptive headlights can refer to other types of adaptation, such as automatic high beams. These headlights automatically switch between low beams and high beams in the presence of traffic. It’s also used to indicate adaptive driving beams. These headlights use complex LED arrays to minimize dazzling other drivers.

Curve-adaptive headlights have bulbs that pivot toward the vehicle’s direction of travel. As the driver turns the steering wheel left or right, or as sensors detect a curvature in the road, the headlights pivot in that direction to better illuminate what’s in the vehicle’s path. Some curve-adaptive headlights also change the bulbs’ angle in relation to vehicle speed to project closer or further.

Cornering lights is another term that is sometimes used to describe curve-adaptive headlights. More specifically, though, cornering lights are auxiliary lights next to or near the main headlights. It’s a simple system that predates modern curve-adaptive headlights.

Whereas many curve-adaptive headlights physically pivot the bulbs in the vehicle’s direction of travel, cornering lights are fixed in place. They automatically activate on the side where the steering wheel is turned, or where the turn signal is activated. As the driver returns the steering wheel to center or the turn signal deactivates, the cornering light switches off. The goal is to temporarily illuminate the area in the vehicle’s direction of travel. Cornering lights have been used in cars for decades, and some new models still use them today.

Automatic high beams are high beams that turn on and off automatically without the driver having to activate them. Unlike conventional high beams, which must be manually engaged, automatic high beams are on by default. A sensor detects the lights of nearby vehicles, whether it’s the taillights of vehicles moving in the same direction, or the headlights of vehicles approaching in oncoming lanes. The sensor turns the high beams off to avoid dazzling those drivers. When there are no other vehicles around, the high beams switch back on to enhance visibility. Although vehicles with automatic high beams default to full brightness, they still let the driver manually control the low beams or high beams if, for example, they want to make sure they don’t blind oncoming traffic for the instant between the car recognizing another vehicle and switching back to low beams.

Adaptive driving beams (ADB) are a newer, high-tech type of adaptive headlight. In fact, ADB headlights are so advanced that they’re prohibited in the U.S. Instead of using distinct bulbs for low and high beams, ADB lights are made up of many individual, very bright LEDs. How the brightness of each LED can be precisely controlled makes ADB headlights special.

When sensors detect other cars, software responds by dimming the LEDs—but only the ones that project onto those vehicles. Meanwhile, the LEDs that aren’t shining on the other vehicles maintain full brightness. Each LED adjusts dynamically to other vehicles’ positions. In this way, there’s bright illumination around those vehicles, but less on them. Think of ADB headlights as illuminating what’s ahead, but projecting “shadow” on other cars to minimize dazzling their drivers.

As smart and high-tech as adaptive driving beams are, they’re not offered in the U.S. Why? Blame FMVSS 108, a regulation within the Federal Motor Vehicle Safety Standard mandating that cars sold in the U.S. must have distinct low beam and high beam patterns. ADB headlights dynamically adapt their pattern and don’t meet that requirement. Various automakers have petitioned the NHTSA to modify FMVSS 108 and allow ADB headlights, but a compromise hasn’t been reached.

Curve-adaptive headlights work with bulbs mounted on motors or servos, which allow the bulbs to pivot. When the driver turns the steering wheel, or when sensors detect a curvature in the road, software or hardware adjust the bulbs in accordance. When the vehicle’s direction returns to straight ahead, so do the bulbs. Some curve-adaptive headlights also change the bulbs’ angle in relation to speed. As speed changes, the headlights point more up or down, casting light closer or further down the road.

Automatic high beams use a sensor, usually one that looks for headlights or taillights, to detect other vehicles. When it does, software switches off the high beams to prevent dazzling other drivers. Once those vehicles pass, the sensor switches the high beams back on. Vehicles equipped with automatic high beams have high beams turned on by default, but still allow manual control between low and high beams.

How adaptive driving beams work is complex. They are composed of numerous small but bright LEDs. Each LED’s brightness can be precisely adjusted by software. Like automatic high beams, a sensor detects the lights of other vehicles. However, instead of turning the entire beam on or off, each LED actively adjusts corresponding to the location of other vehicles. Each LED dims or brightens as those vehicles approach or pass, creating an area of “shadow” around them. Adaptive driving beams provide high brightness around other vehicles, but low brightness directly on them, which maximizes visibility without dazzling other drivers. Some systems are better than others at reducing glare for oncoming traffic.

Adaptive headlights are trickling down from high-end to mainstream vehicles, but they are sometimes an optional extra. Nonetheless, choosing a system that helps avoid hazardous situations seems like a worthwhile expense. Being able to see a few feet further ahead, or slightly more around a corner, could make a huge difference. An avoidable crash could cost much more than the adaptive headlight option.

IIHS studies show that insurance claims are reduced in vehicles with adaptive headlights. However, it’s not clear to what degree this reduction results from adaptability or their brighter bulbs. Also, when it comes to advanced car safety features, automatic emergency braking is still a more important investment.

Adaptive headlights have some other cost considerations. If a headlight has a problem, it’ll be more expensive to repair than a conventional equivalent. That’s compounded by potential damage to the sensors that control them, which are typically mounted in the front bumper or behind the windshield. Even a minor parking collision or cracked windshield could incur costly replacements or recalibrations.

High-end manufacturers include or offer adaptive headlights on many of their cars. Porsche, BMW, Audi, Mercedes-Benz, and Volvo are a few that feature some type of adaptive headlights on much of their range. Many mainstream vehicles now have adaptive headlights, too. Ford, Subaru, Toyota, Hyundai, and Honda are among automakers that include adaptive headlights even on some entry-level models. The number of car models with adaptive headlights grows each model year.

Knowing if your car has adaptive headlights may be as simple as going for a drive in the dark. If you notice your headlights changing their angle or brightness without you doing anything, your headlights are likely adaptive. Some manufacturers put script or an icon denoting their adaptive headlight system inside the lens. Take a look—when the headlights are off—to see what’s there. Adaptive headlights started to become more common from the early 2010s, so if your car was built before then, its headlights probably are not adaptive.